Slartibartfast is a Magrathean, and a designer of planets. His favourite part of the job was creating coastlines, the most notable of which were the fjords found on the coast of Norway on planet Earth, for which he won an award. While Arthur Dent and Ford Prefect were on ancient Earth, they saw Slartibartfast's signature deep inside a glacier in ancient Norway.
When Earth Mk. II was being made, Slartibartfast was assigned to the continent of Africa. He was unhappy about this, because he wanted to make more fjords (arguing that they give a continent a baroque feel), and fjords in Africa would be hard for him to explain without natural glacial movement.
In any event, the new Earth was not required and, much to Slartibartfast's disgust, its owners suggested that he take a quick skiing holiday on his glaciers before dismantling them.
Slartibartfast joined the Campaign for Real Time (or CamTim as the volunteers casually refer to it) which tries to preserve events as they happened before time travelling was invented. He picks up Arthur and Ford from Lord's Crickett Grond with his Starship Bistromath, after which they head out to stop the robots of Krikkit from bringing together the pieces of the Wickett Gate.